When an electroless plating step is to be applied to a semiconductor substrate, a catalytic metal must be formed on the semiconductor substrate in advance.
Patent Literature 1 discloses that a semiconductor substrate is dipped in a catalytic metal solution containing 0.2 [ppm] or less of dissolved oxygen to deposit catalytic metal while suppressing oxidation on a semiconductor substrate surface.
Patent Literature 2 discloses that a silicon substrate is dipped in a catalytic metal solution containing hydrofluoric acid and ammonium fluoride to deposit catalytic metal while removing an oxide on the surface.
Patent Literature 3 discloses that catalytic metal is formed in a non-through hole of a silicon substrate to form an electroless plating film (metal film) having good adhesion.